Compression flexometer and method of testing rubber and the like



Jan. 26, 1932. F. D. ABBOTT 1,843,074

COD/[PRESSION FLEXOMETER AND METHOD OF TESTING RUBBER AND THE LIKE Filed Aug. 27, 192s 0 E [III l l O- INVENTOR.

7km/AZZ /Yaaorz 2 A BY f f uui'riin STATES ser;

FRANZ n. ABBOTT, or AKRON, OHIO, essieu/ORTO Tian riiiiisroim 'rien 'ay RUBBER Patented Jan. ze, 1932 orrori COMPANY, OF AKRON, OHIO, .A CORPORATION .0F OHIO vCOIVIVIPRIESSION FLEXOMETER AND METHOD TESTNG UBBER AND THE LLKE f apnea/cian sied August 27, i928. seria'. No."aoaaia methodof testing rubber and the like.

VTests*determining moduli and tensile i strength, permanent set at break, hardness,

etc., of rubber Vand the like are knot of any Y valuek in determining theeiiect of iiexure under compression or the 'amount of permanent setdue to the fatigue or hysteresis loss revsultingiroin fleXure and heating of rubber While under compression. The general purpose of this invention, therefore, is todevise apparatus and procedure fortesting rubber to determine such eifectsrand to study rubber compounds which go into the manufacture oi" shock insulators,y torque absorbers, flexible couplings and the .like :Where the rubber is subjected inservice to conditionsof compression and iiexure; y y,

e Anobject of the invention is to devise an apparatus comprising means for compressing a sample otrubber'or like material tol'be tested and means for rapidly flexingthe inaterial to and fro in a straight-line direction, or anguiarly or both While under compression. Another object of the invention is ,to

-devisea simple and -eii'ective rmachine .for testing the effector compression and flexurc the degree of temporaryand permanent set or-to measure the time required' to produce blowout of the test specimen. Y

The foregoing and otlienobjects'are ob tained by-'the devices illustrated in the accompanying dravvingsrk and described below.

VIt is to be understood that the' invention is not limited'to'the speciic forms thereof ydisclosed lie-rein.v

l the accompanying. dra-Wings,

`fvy'vFigure 1 is a plan view. of an apparatus enibodying'theprinciples of the invention ;V

" Figure `2 is a side elevation 'thereof partlyk broken away; r 1

- Figure 3 is an end elevation. thereof; and

' Figure 1- is'an elevation of a specimen which has been tested. f

`Referring in detail to the drawings, the numeral denotes a base plate provided Withk bearings 11, 11 invvliicli arejournaled bolts 12, 12 ffor clamping rthe top plate 13. Each bolt 12 passesthrough a trunnion 14 journaled in ab bearing 15 attached to the top of yplate 13., 'A connecting arm 16 ispivoted at one end to a-bearing 17 provided in the center of top piate13, and is securedat the other end;

to ,a cross-head 18 which is reciprocable by means oiconnecting rods 19,19 pivotally secured to crank pins'20, 20 eccentrically mount*v ed with respect tou'otatable heads 21, 21. Each head 21 is provided With a slot 22 Whereby the eccentricity of the crank pin 20 With respect to head -21 may be adjusted to Obtain any desired amplitude of movement in connectingrod 19.A "Heads 21 are aliixed to shaft 23 suitably journaicd in hangers 24, 2K1, the sliaf't being rotated by pulley 25 keyed thereto, and having trained thereover a belt 26 driven by any suitable source of power (not shown).

On base plate 10 is mounted an angularly movable plate 27 support-ed on a thrustbearing 28 andoscillatable by means of arm 29 connected thereto. Arm 29 is reciprocated in a horizontal plane by means of connecting rod 30 having ball and socket engagement therewith, connecting rod 30 being pivoted to a leverl 31 actuated by cross-head 18. Lever 31 is formed with a yoke portion 32 'for engagement with cross-head 18 and is pivoted adjacent its central portion by meansof a pin 33 projecting from a support 3d, lever 31 being formed with a slot 35 by means of which its point oiI pivotal engagement with pin 33 may be adjusted for varying the am plitud-e of movement of connecting rod 30.

If desired, dead Weight 36, as indicated by dotted lines in Figure 2, may be mounted on the top plate in order to maintain a constant vpressure ou the specimen irrespective oit the flat specimens ory with spherical or other 'shaped seats where other Vshapes of vspecimens are to be tested. Figure 2 illustrates mounted Vin the apparatus a'specimen comprising a block of rubber 38 which has been vulcanized to metal plates39, 39. Yligure4 illustrates a test specimen 401-comprising a y plain block of rubber or like material which has been subjected to the flexing and compressing action of 'the apparatus and jhas been afterwards Vcut in half'to show the sectional shape of the specimen.

:[nfthe operation of the device for testing the eHect of compression andflexure on a sample of rubber or likematerial, the following` preferred method of'procedure has been devised. Y. i i

f A specimen isplacedbetween vblocks '37 when Vplate 13 isat itsdead centerpositionV as shownmin V"Figure.-2,and compressed 'by' tightening Vthe nutsfon bolts 12. 'While any degree of Ycompression may be applied to suit' the vrequirements.of particular tests, it is foundpreferable 'inorder to obtainfuniform results to compress the'specimen to one-half its/normal fthickness,'this 50%-deflecti0n' being measured `by' a suitable scale. The Vmachine vis then' put in' motion to `reciprocate 2rap'id`ly the top plate 13 yandto oscillate `the 3f angularly movable bottom plate'27 or to carry vout .either -olf these motions individually, the

frequency and amplitude of vibration of the plates being preferably "in the .orderV of 1800 cycles Vper'minute with a Athro-w -of kthreeeighths of an inch.V It `will be understood that onlyone flexing motion vmay :beimparted to the specimen undercompressiemifdesired,

and that either cdnnecting rod or con'- n'ectin'g rod 16 may Ybe disconnected for this purpose in order to obtain respectivelyonly the -trans'latory vmoitici-n or onlythezoseillatory f motiomasdes'iredi The duration lef flexure Vdepends-ulpon the sizeof lthe sample vanelli-upon', the results "to 'be f Obtained, 'varying y'from `five)minutes ulto t-woy hours vrusuallyi'for-testing permanent Vset of the material, or for longer periods io-ftime where it -is-desiredtaobtain-blowout of' the specimen. Thespecnnen `1s{flexed-fora suit-v able yperied of time,1then removed, yiga'uged :te y ydetermine the minimum rthickness and-allowed tc-standvfor another hour`.;"The specirce.

men fis" then bisected in aA vertical plane lin the direction of flexure byA cutting down through thecenterf ofthe material -igure- L1) and is again -gauged/tomeasure the minimum height The figures obtain-ed may be'usedt'o calculate the 'percentage cf temporaryiset inthey rubber, the 'percentage of recbvery land the' percentage of rpermanent set- V ,l *In testing"forjblowout theI specimen -is' flexed continueuslyuiitil ail/explosion or'snd-fY Y den collapse of the vmaterial occursdue tol intense'jheatjand pressurjddeveloped inrthe Y material causingfthe internal portions to be-v of a heat-insulating material.

torted and permanently'setto a greater de;

gree than the better grades of rubber. The

. apparatus is especially vuseful ,in .determining the quality' of ru'b'ber compounds to 'be used inshock absorbersorfthe like where the rubber in service is subjected to compression and fiexure. l/Yhere. the rubber isf tov bebonded to metal plates, :the apparatus is also valuable in .detcrminingitheeffectof liexure :tending tto` separate .the rubber ffrcmthe 'metalito which 1t is vulcanized. 11i-.the latterV test the specimen may be flexed withoutbeingplaced under 1 compression. i

Modification ofthe construction and .pro-

cedure disclosed. herein may be .resorted to Without Adeparting from vthe spirit of the vinvention orathe scope ltherec'fas defined 'bythe appended claims. Y Vhat is' claimed is f f Y l. Apparatus for-testing rubber andthe like, comprising top and'bottom relatively movablev plates between which `a specimen to be testedfmay lbe clamped, :bolts pivotally connected Jto leach .of said plates. lfor clampj ing `the same .together to' compress the .specimen, .an Yangularly oscillatable r`member mounted on the lower plate for .engagement with the'bottom Aof the specimen, means for reciprocating :the topplate,1neans for oscillating said member, and ,means for adjust ing the amplitudes of the reciprocation and the oscillation respectively ofls'aidfplate .and member.

2.. Apparatusffo'r testing rubber Vand the like, :comprisingt'op and'bottom relatively movable plates between Vwhich specimen to ybe testedzmay be clamped, Ib'oltspivotallyV connected toeach ofl Vsaid vplates for clamping the samev together fto compress the specimen,

an angularly oscillatable `member mounted` on `the lowerY plate rfor* engagement Vwith the .bottom `of vthe specimen, means for reciprocatingtheV top plate, and means for oscillatingsaid member; n l. i

i 3. Apparatus for testing 'rubber andthe like, comprising top andbottom relatively 'ingsaid plates togetherto lcompress the speci-4 men, an `mgularly ;,osc'illatablef member mounted on the lower plate for" engagement `with thebottom oflthe specimen, means for reciprocating the top plate,f'and means for oscillating 'said member.

4. Apparatus fortesting resilient" and com-i `pres'sible material, Vsaid 'apparatus .comprismovable plates between` which a fspecimenftov be tested maybe clamped,vmean sfor clamp-I men,

(ing upper and lower members between which a specimen to be tested may be clamped, one of said members being reciprocable with a translatcry motion, the other of said members being angularly oscillatable, means for compressing said specimen between said members, means for reciprocating the first of said members, and means for oscillating the second of said members.

Y 5. A machine for testing rubber or the like, comprising a pair of members for clamping a specimen to be tested, one of said members being reciprocable in a horizontal plane, the other of said members being angularly oscillatable in a plane substantially parallel to the plane of motion of the first member, means for urging said members relatively together to clamp a test specimen therebetween, means for reciprocating the first member, and means for oscillating the second member.

6. A machine for testing resilient compressible material, comprising means for compressing a test specimen, means for flexing .one surface of the specimen to and fro with respect to another surface, and means for twisting the latter surface with respect to the first-named surface.

7. Material testing apparatus comprising a pair of specimen clamping members relatively movable in substantially parallel planes,.means for compressing the specimen to be testedbetween said members, means for reciprocating one of said members, and means for angularly oscillating the other of said members.

8. Apparatus for testing rubber and the like, comprising upper and lower relatively movable plates between which a specimen to be tested may be clamped, bolts pivotally connected to each of said plates for clamping the same together to compress the specimen, and means for reciprocating one of said plates to flex the specimen. Y

9. Apparatus for testing rubber and the like, comprising upper and lower relatively movable plates between which a specimen to be tested may be clamped, bolts pivotally connected to each of said plates for clamping the same together to compress the specian angularly oscillatable member mounted on one of said plates for engagement with one surface of the specimen, and

f the specimen.

means for oscillating said member to twist 10. Apparatus for testing rubber and the y like, comprising relatively movable plates between which a specimen to be tested may be clamped, means for clamping said plates together to compress the specimen, an angularlyY in reverse directions.

11.Y A machine for testing permanent distortion of resilient compressible materials due to flexnre while under compression, said machine comprising means for compressing a test specimen of the material, and means for twisting one surface of the specimen to and fro relatively to an opposed surface thereof while the specimen is under compression.

12. Apparatus for testing rubber and the like, comprising means for compressing a specimen of the material, and means for relatively flexing to and fro two opposed surfaces of the specimen and distorting the body of rubber therebetween while the latter is under compression.

18. Apparatus for testing rubber and the like, comprising means for compressing a specimen of the material, and means for relatively angularly 'twisting two opposed surfaces of the specimen alternately in reverse directions while the latter is under compression.

14. Apparatus for testing rubber and the like, comprising means for applying a constant load on the vspecimen to be tested for compressing` the same, and means for relatively fl to and fro two opposed surfaces lof the specimen and distorting the body of rubber therebetween while the latter is under coi'npression.

15; Apparatus for testing rubber and the like, comprising` means for applying a constant load on the specimen te be testedfor compressing the same, and means for relatively angularly twisting two opposed surfaces of the specimen alternately in reverse directions while the latter is under compression.

16. A method of testing rubber or like material, comprising compressing a specimen of said material, flexing the specimen while it is under compression, releasing the compression, measuring the difference in nimensions from the original dimensions, permitting the specimen to reco-ver, bisecting the specimen to disclose the degree of permanent distortion resulting from compression and fleXure, and determining the amount of recovery and the amount of permanent distortion.

17. A method of testing rubber or like material, comprising compressing a specimen of said material, flexing the specimen laterally and angularly while it is under compression, releasing the compression, and measuring the amount of distortion of the specimen.

18. A method of testing rubber or like material, comprising compressing a specimen of said material, flexing the specimen to and fro while it is under compression to develop frictional heat therein and to distort the specimen, releasing the compression, and measuring the amount of distortion of the specimen.

19. A method of determining temporary and permanent set of rubber or the like when subjected to fleXure and compression, which yccnnprises 'compressing a specimen to' be lcr:

testedV reciprocably Vflexing one surface of the specimen With yrespect Ato any opposed surface,

angularly tvvistng'said'opposed sur/face with l respect toV said irstfnamed surface, releasing compression on the specimen, measuringvariationso thespecimen from its original .dimensions, permittingvthe specimen to stand untilrecovered lfrom its temporary set, and measuring again to determine permanent set. 20. A method of determining ytemporary and permanent set of rubber or the like whenY subjected to eXure and compression, which comprises compressing a specimen to be tested," reciprocably'exing one surface of the 'Y specimen with respect to lan opposed surface,

`releasing compression on the specimen, measuring variations of the specimen from its original dimension7 permitting the specimen to kstand until recovered `from its temporary set, and measuring again to determine permaVn nent set.

21. Al method of determining temporary and permanent set of rubber or the like When subjected to fexure and compression, whichV comprises compressing a specimen to be tested, angularly twisting one'surface of the specimen With respect to anopposed surface, n

releasing compression on the specimen, measuring variations of the specimen from its original dimension, permitting the specimen to stand until recovered from its temporary set, and measuringagain todetermine perma# nentset.` f r. Y

In Witness whereof l' have hereunto atixed my signature this 14th dav of August, 1928.

FRANZ D. ABBOTT. 

